You can also create complete Logfiles with generated text in a single
step:

self.addCompleteLog('warnings', text)

When the step is done, it should call self.finished(result). 'result'
will be provided to the buildbot.process.base.Build, and should be one of the
constants defined above: SUCCESS, WARNINGS, FAILURE, or SKIPPED.

If the step encounters an exception, it should call self.failed(why).
'why' should be a Failure object. This automatically fails the whole
build with an exception. It is a good idea to add self.failed as an
errback to any Deferreds you might obtain.

If the step decides it does not need to be run, start() can return the
constant SKIPPED. This fires the callback immediately: it is not
necessary to call .finished yourself. This can also indicate to the
status-reporting mechanism that this step should not be displayed.

A step can be configured to only run under certain conditions. To do
this, set the step's doStepIf to a boolean value, or to a function that
returns a boolean value. If the value or function result is False, then
the step will return SKIPPED without doing anything, otherwise the step
will be executed normally. If you set doStepIf to a function, that
function should accept one parameter, which will be the Step object
itself.

interrupt(self,
reason)

Halt the command, either because the user has decided to cancel the
build ('reason' is a string), or because the slave has disconnected
('reason' is a ConnectionLost Failure). Any further local processing
should be skipped, and the Step completed with an error status. The
results text should say something useful like ['step', 'interrupted'] or
['remote', 'lost']